Downhole plug assembly

ABSTRACT

An apparatus includes a body member and a ring member. The body member has a through passageway, and the body member includes an outer engagement surface. The ring member has a contracted state and an expanded state, and the ring member includes an inner engagement surface and an outer surface. The seal member is adapted to axially move with respect to the body member in response to the application of an axial force such that the outer engagement surface of the body member physically engages the inner engagement surface of the ring member to radially expand the ring member to transition the ring member to the expanded state and cause the outer surface of the ring member to contact an inner wall of a tubing string. The physical engagement of the inner engagement surface of the ring member with the outer engagement surface of the body member forms a seal between the ring member and the body member. The contact of the outer surface of the ring member with the tubing string forms a seal between the ring member and the tubing string and secures the ring member to the tubing string. The inner engagement surface and the outer engagement surface are adapted to physically interact to retain the ring member in the expanded state when the axial force is removed.

BACKGROUND

For purposes of preparing a well for the production of oil or gas, atleast one perforating gun may be deployed into the well via a conveyancemechanism, such as a wireline, slickline or a coiled tubing string. Theshaped charges of the perforating gun(s) are fired when the gun(s) areappropriately positioned to perforate a casing of the well and formperforating tunnels into the surrounding formation. Additionaloperations may be performed in the well to increase the well'spermeability, such as well stimulation operations and operations thatinvolve hydraulic fracturing. The above-described perforating andstimulation operations may be performed in multiple stages of the well.

The above-described operations may be performed by actuating one or moredownhole tools (perforating guns, sleeve valves, and so forth) and byforming one or more fluid-diverting fluid barriers downhole in the well.

SUMMARY

The summary is provided to introduce a selection of concepts that arefurther described below in the detailed description. This summary is notintended to identify key or essential features of the claimed subjectmatter, nor is it intended to be used as an aid in limiting the scope ofthe claimed subject matter.

In accordance with an example implementation, a technique includesrunning a plug assembly inside a tubing string of a well; and settingthe plug assembly. Setting the plug assembly includes axially, moving aseal member of the plug assembly with respect to a body member of theplug assembly to cause an outer engagement surface of the body member tophysically engage an inner engagement surface of a ring member of theplug assembly to radially expand the ring member to transition the ringmember to an expanded state and cause an outer surface of the ringmember to contact an inner wall of the tubing string; using the physicalengagement of the inner engagement surface of the ring member with theouter engagement surface of the body member to form a seal between thering member and the body member; using contact of the outer surface ofthe ring member with the tubing string to form a seal between the ringmember and the tubing string and secure the ring member to the tubingstring; and using a physical interaction between the inner engagementsurface and the outer engagement surface to retain the ring member inthe expanded state when the axial force is removed.

In accordance with another example implementation, a system that isusable with a well includes a tubing string, an untethered object and aplug assembly. The plug assembly includes a body member and a ringmember. The body member has a through passageway, and the body memberincludes an outer engagement surface and a seat that is adapted to catchthe untethered object to form a fluid barrier in the tubing string. Thering member has a contracted state and an expanded state; and the ringmember includes an inner engagement surface and an outer surface. Theseal member is adapted to axially move with respect to the body memberin response to the application of an axial force such that the outerengagement surface of the body member physically engages the innerengagement surface of the ring member to radially expand the ring memberto transition the ring member to the expanded state and cause the outersurface of the ring member to contact an inner wall of the tubingstring. The physical engagement of the inner engagement surface of thering member with the outer engagement surface of the body member forms aseal between the ring member and the body member. The contact of theouter surface of the ring member with the tubing string forms a sealbetween the ring member and the tubing string and secures the ringmember to the tubing string. The inner engagement surface and the outerengagement surface are adapted to physically interact to retain the ringmember in the expanded state when the axial force is removed.

In accordance with yet another example implementation, an apparatusincludes a body member and a ring member. The body member has a throughpassageway, and the body member includes an outer engagement surface.The ring member has a contracted state and an expanded state, and thering member includes an inner engagement surface and an outer surface.The seal member is adapted to axially move with respect to the bodymember in response to the application of an axial force such that theouter engagement surface of the body member physically engages the innerengagement surface of the ring member to radially expand the ring memberto transition the ring member to the expanded state and cause the outersurface of the ring member to contact an inner wall of a tubing string.The physical engagement of the inner engagement surface of the ringmember with the outer engagement surface of the body member forms a sealbetween the ring member and the body member. The contact of the outersurface of the ring member with the tubing string forms a seal betweenthe ring member and the tubing string and secures the ring member to thetubing string. The inner engagement surface and the outer engagementsurface are adapted to physically interact to retain the ring member inthe expanded state when the axial force is removed.

Advantages and other features will become apparent from the followingdrawings, description and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are schematic diagrams of a well illustrating the use ofa plug assembly in connection with a well stimulation operationaccording to an example implementation.

FIGS. 2 and 5 are perspective views of plug assemblies according toexample implementations.

FIG. 3A is a cross-sectional view of a portion of a well illustratingthe running of the plug assembly of FIG. 2 into a tubing stringaccording to an example implementation.

FIG. 3B is a cross-sectional view of the portion of the wellillustrating the setting of the plug assembly in the tubing stringaccording to an example implementation.

FIG. 3C is a cross-sectional view of the portion of the wellillustrating a fluid barrier formed in the tubing string using the plugassembly according to an example implementation.

FIG. 4 is an illustration of physical interaction of ratchet teeth of aseal member with ratchet teeth of a plug assembly of a body member ofthe plug assembly according to an example implementation.

FIG. 6A is a cross-sectional view of a portion of the well illustratingthe running of the plug assembly of FIG. 5 into a tubing stringaccording to an example implementation.

FIG. 6B is a cross-sectional view of the portion of the wellillustrating the setting of the plug assembly in the tubing stringaccording to an example implementation.

FIG. 6C is a cross-sectional view of the portion of the wellillustrating a fluid barrier formed from the plug assembly of FIG. 5according to an example implementation.

FIG. 7 is an illustration of physical interaction of an engagementsurface of a seal member of a plug assembly with an engagement surfaceof a body member of the plug assembly according to an exampleimplementation.

FIG. 8 is a flow diagram illustrating a technique to form a fluidbarrier in a tubing string according to an example implementation.

DETAILED DESCRIPTION

In the following description, numerous specific details are set forthbut implementations may be practiced without these specific details.Well-known circuits, structures and techniques have not been shown indetail to avoid obscuring an understanding of this description. “Animplementation,” “example implementation,” “various implementations” andthe like indicate implementation(s) so described may include particularfeatures, structures, or characteristics, but not every implementationnecessarily includes the particular features, structures, orcharacteristics. Some implementations may have some, all, or none of thefeatures described for other implementations. “First”, “second”, “third”and the like describe a common object and indicate different instancesof like objects are being referred to. Such adjectives do not implyobjects so described must be in a given sequence, either temporally,spatially, in ranking, or in any other manner. “Coupled”, “connected”,and their derivatives are not synonyms. “Connected” may indicateelements are in direct physical or electrical contact with each otherand “coupled” may indicate elements co-operate or interact with eachother, but they may or may not be in direct physical or electricalcontact. Also, while similar or same numbers may be used to designatesame or similar parts in different figures, doing so does not mean allfigures including similar or same numbers constitute a single or sameimplementation. Although terms of directional or orientation, such as“up,” “down,” “upper,” “lower,” “uphole,” “downhole,” and the like, maybe used herein for purposes of simplifying the discussion of certainimplementations, it is understood that these orientations and directionsmay not be used in accordance with further example implementations.

In accordance with example implementations, a plug assembly may be runinto a tubing string (a casing string, for example) of a well forpurposes of forming a fluid barrier at a target downhole location. Forexample, the plug assembly may be run downhole inside the tubing stringon a conveyance mechanism (a coiled tubing string or a wireline, asexamples), and when the plug assembly is at the target location, asetting tool may be actuated for purposes for causing the plug assemblyto radially expand to engage the wall of the tubing string to anchor theplug assembly in place. Moreover, in the setting of the plug assembly, afluid seal may be formed between the plug assembly and the tubing stringwall. The plug assembly may have a through passageway that may beblocked to form a fluid obstruction, or barrier, by deploying anuntethered object (an activation ball, for example) inside the tubingstring passageway such that the untethered object travels down throughthe tubing string passageway to land in an internal seat of the plugassembly.

The fluid barrier may be used in connection with a well stimulationoperation. For example, in accordance with some implementations, thefluid barrier may be used to divert fluid to the surrounding formationin a hydraulic fracturing operation.

In accordance with example implementations, the plug assembly includes asealing member, or ring, which is radially expanded downhole inside thetubing string for purposes of securing, or anchoring, the plug assemblyto the tubing string wall and forming a seal for the plug assemblybetween the sealing ring and the tubing string wall. In accordance withexample implementations, the sealing ring has both an inner profile andan outer profile, which do not significantly change (other than havingincreased corresponding diameters) when the sealing ring is transitionedfrom its radially contracted state to its radially expanded state. Thepreservation of these profiles allows an inner engagement surface of thesealing member to be used to both anchor and seal against a body memberof the plug assembly.

More specifically, in accordance with example implementations, the plugassembly has a tapered inner engagement surface that is constructed tophysically engage an outer engagement surface of the body member forpurposes of radially expanding the sealing ring. Moreover, theengagement of these surfaces locks, or anchors, the positions of thesealing ring and body member with respect to each other, forms a fluidseal between these elements and in general, secures the plug assembly inplace in the tubing string.

In accordance with various example implementations that are describedherein, the tapered engagement surfaces of the sealing ring and bodymember of the plug assembly may be smooth surfaces; surfaces havingratchet teeth; surfaces having smooth portions and portions havingratchet teeth; and so forth.

As a more specific example, FIG. 1A depicts a well 100 in accordancewith some implementations. The well 100 includes a laterally extendingwellbore 120, which traverses one or more hydrocarbon-bearingformations. For the specific implementation depicted in FIG. 1A, thewellbore 120 is lined and supported by a tubing string 130. The tubingstring 130 may be cemented to the wellbore 120 (i.e., the tubing string130 may be a casing); or the tubing string 130 may be anchored orsecured, to the surrounding formation(s) by one or multiple packers(i.e., the tubing string 130 may be installed in an “open holewellbore”). For the specific example of FIG. 1A, the tubing string 130is a casing that has been run into the wellbore 120, and a cementingoperation has been performed to place cement 140 in the annular regionbetween the exterior of the casing and the wall of the wellbore 120.

It is noted that although FIG. 1A depicts a laterally extendingwellbore, the technique systems that are disclosed herein may likewiseapply to vertically extending wellbores. Moreover, in accordance withexample implementations, the well 100 may contain multiple wellbores,which contain tubing strings that are similar to the tubing string 130of FIG. 1A. The well 100 may be a subsea well or may be a terrestrialwell depending on the particular implementation. Additionally, the well100 may be an injection well or may be a production well, depending onthe particular implementation. Thus, many implementations arecontemplated, which are within the scope of the appended claims.

As depicted in FIG. 1A, the tubing string 130 extends from a heel end141 of a lateral segment 121 of the wellbore 120 to a toe end 143 of thesegment 121. The lateral segment 121 may be associated with multiplestages, which may be isolated and stimulated separately.

For the specific example depicted in FIG. 1A, a plug assembly 150 hasbeen set and thus, anchored, or secured, to the tubing string 130 at atarget downhole location. For this example, the plug assembly 150 islocated in a zone, or stage, of the well 100 to be fractured. In thismanner, as shown in FIG. 1A, hydraulic communication with thesurrounding formation may have been enhanced through, for example, aperforating operation that formed perforations 134 that extend throughthe surrounding tubing string wall and into the surrounding formation.Hydraulic communication may be enhanced using other techniques (abrasivejetting operations, for example). The plug assembly 150 may be set atthe lower end of the zone to be fractured, as illustrated in FIG. 1A.

Referring to FIG. 1B, an untethered object (an activation sphere, orball 170, as an example), may be deployed inside the central passagewayof the tubing string 130 to land in a seat 154 of the plug assembly 150for purposes of sealing a through passageway of the set plug assembly toform a fluid barrier inside the tubing string 130. In this regard, afterthe fluid barrier is formed, a well stimulation operation may beperformed that relies on the fluid barrier. For example, a hydraulicfracturing operation may be performed in which a fracturing fluid ispumped into the tubing string 130, and the fluid barrier diverts thefluid into the surrounding formation.

In the context of this application, an “untethered object” refers to anobject that is communicated downhole through the passage of a tubingstring along at least part of its path without the use of a conveyanceline (a slickline, a wireline, a coiled tubing string, and so forth). Asexamples, the untethered object may be a ball (or sphere), a dart or abar. Regardless of its particular form, the untethered object travelsthrough the passageway of the tubing string to land in the objectcatching seat of the plug assembly to form a corresponding fluidobstruction, or barrier.

Referring to FIG. 2, in accordance with example implementations, theplug assembly 150 includes a sealing member, or ring 220, which has twostates: a radially retracted state for purposes of running the plugassembly 150 downhole inside a tubing string; and a radially expandedstate for purposes of anchoring and sealing the plug assembly 150 to thetubing string wall. As depicted in FIG. 2, in accordance with exampleimplementations, the sealing ring 220 may be a slotted metal sealingring similar to a slotted metal sealing ring that is described in U.S.Patent Publication No. US 2016/0333661, entitled, “METAL SEALINGDEVICE,” which has a publication date of Nov. 17, 2016, and is herebyincorporated by reference in its entirety. Sealing rings other than aslotted metal sealing ring may be used, in accordance with furtherexample implementations.

The plug assembly 150 further includes a tubular body member 230. Ingeneral, the body member 230 has an outer, tapered surface (not depictedin FIG. 2), which engages an inner tapered surface (not depicted in FIG.2) of the sealing ring 220 for purposes of radially expanding thesealing ring 220. Moreover, the contacting tapered services both secure,or anchor, the sealing ring 220 to the body 230 to lock, or secure, thesealing ring 220 in its radially expanded state and form a fluid sealbetween the sealing ring 220 and the body member 230.

As depicted in FIG. 2, in accordance with some implementations, the plugassembly 150 may be run downhole inside the tubing string 130 on asetting tool, which includes a setting sleeve 210 and an inner mandrel.More specifically, when the plug assembly 150 is at the target downholelocation in which a fluid barrier is to be formed, an actuator (notshown in FIG. 2) produces an axial force along a longitudinal axis 201to shear, shear screws 214 (which confine movement of the setting sleeve210 when the plug assembly 150 is being run downhole) to allow thesetting sleeve 210 to move axially along the longitudinal axis 201 andforce the sealing ring 220 against the body member 230 to transition thesealing sleeve 220 into its regularly expanded state.

Among the other features of the plug assembly 150, in accordance withsome implementations, the plug assembly 150 may include one or multipleslips 256 for purposes of enhancing the anchoring of the plug assembly150 to the tubing wall, one or more corresponding slip bases 260 forpurposes of forcing the slips 256 against the tubing wall in response tothe axial movement of the setting sleeve 210, and a shear ring 254 forpurposes of confining movement of the slip base(s) 260 during therunning of the plug assembly 150 downhole. Moreover, as depicted in FIG.2, in accordance with some implementations, the setting tool may includea lower body member 250 for purposes of providing a downhole stopagainst which the setting sleeve 220 acts to radially expand the sealingring 220.

FIG. 3A is a cross-sectional view depicting the running of the plugassembly 150 downhole inside the tubing string 130. As shown, in thisstate, the plug assembly 150 has an overall radially contracted outerdiameter to allow the plug assembly 150 to freely pass through thecentral passageway of the tubing string 130. When the plug assembly 150is at the targeted downhole location inside the tubing string 130, thesetting tool may then be remotely activated (via a wireline-communicatedcommand, for example), which causes the setting tool to apply an axialforce to the setting sleeve 210 to set the plug assembly, as depicted inFIG. 3B. In this manner, as shown in FIG. 3B, the setting sleeve 210translates along the longitudinal axis 201 and contacts the uphole endof the sealing ring 220 to cause an inner tapered surface 312 of thesealing ring 220 to slide against a tapered outer surface 312 of thebody member 230. Axial movement of the sealing ring 220, in turn, causesthe sealing ring 220 to radially expand, due to the interaction of thetapered surfaces 310 and 312. Continued movement of the setting sleevecontinues until, as depicted in FIG. 3B, an internal annular shoulder ofthe setting sleeve 210 contacts an uphole end of the inner mandrel ofthe setting tool to cause the mandrel to move the lower body member 250to sheer pins 252 to release the setting tool from the plug assembly150. Before the setting tool is released, however, the movement of theinner mandrel engages an inner surface of the body member 230 to causethe body member 230 to act against the slip bodies 260 to radiallyexpand the slips 256.

FIG. 3C depicts the plug assembly 150 after removal of the setting tooland after deployment of an untethered object (such as an activation ball330), which lands in an internal, annular seat of the body member 230 toform a fluid seal in the interior passageway of the plug assembly 150.Moreover, with this internal fluid seal and the corresponding fluidseals formed between the body member 230 and seal ring 220, and the sealbetween the sealing ring 220 and the tubing string wall, a fluid barrieris formed inside the tubing string 130.

Referring to FIG. 4, in accordance with example implementations, theinner surface 310 of the sealing ring 220 may include annularlyextending ratchet teeth 412, which are constructed to engagecorresponding ratchet teeth 414 of the outer engagement surface 312 ofthe body member 230. In this manner, the axial force produced by thesetting tool slides the ratchet teeth 412 with respect to the ratchetteeth 414 so that when the axial force is removed (due to the release ofthe setting tool), the interaction between the ratchet teeth 412 and 414secures, or anchors, the sealing ring 220 relative to the body member230. Moreover, in accordance with some implementations, the engagementof the ratchet teeth 412 and 414 form a fluid seal between the sealingring 220 and the body member 230.

In accordance with some implementations, the tapered surface of thesealing ring 220 may be at an angle between 5 to 10 degrees of thelongitudinal axis 210, and in accordance with some implementations, theangle may be approximately 7 degrees. Moreover, in accordance withexample implementations, the tapered surface of the body member 230 mayhave the same taper angle as the taper angle for the sealing ring 220.

In accordance with further example implementations, a plug assembly mayhave a sealing ring and body member, which have corresponding taperedsurfaces without ratchet teeth. More specifically, referring to FIG. 5,in accordance with further example implementations, a plug assembly 500may be deployed downhole and include a sealing ring 520, which has aninterior, tapered and smooth surface (not depicted in FIG. 5) that isconstructed to physically engage a corresponding exterior tapered andsmooth surface (not depicted in FIG. 5) of a body member 530. Ingeneral, some elements of the plug assembly 500 are similar to the plugassembly 150 (FIG. 2), with different reference numerals, such asreference numerals 520 and 530, being used to denote different elementsfor the plug assembly 500.

Referring to FIG. 6A, similar to the plug assembly 150, the plugassembly 500 may be run downhole inside the tubing string 150 in aradially contracted state and radially expanded, as depicted in FIG. 6B,for purposes of setting the plug assembly 500. In this manner, as shownin FIG. 6B, the setting of the plug assembly 500 includes axially movingthe setting sleeve 210 to cause the sealing ring 520 to regularly expanddue to the physical interaction between a smooth tapered interiorsurface 610 of the sealing ring 520 with a relatively smooth exteriortapered surface 612 of the body member 530.

The tapered surfaces 610 and 612, in turn, perform dual functions, inaccordance with example implementations: the tapered surfaces 610 and612 form a fluid seal between the sealing ring 520 and body member 530;and the tapered surfaces 610 and 612 secure, or lock, the sealing ring520 to the body member 530 due to a frictional contact force, whichresists axial separation of these elements when the setting tool removesthe axially applied force to leave the plug assembly 150 set inside thewell, as depicted in FIG. 6C. Moreover, as depicted in FIG. 6C, anuntethered object such as the activation ball 330, may be deployedinside the tubing string 130 to land in a seat of the body member 530for purposes of forming a fluid barrier inside the tubing string 130.

In accordance with example implementations, the smooth, tapered surfaces610 and 612 may each have a tapered angle with respect to thelongitudinal axis 201 between 5 to 10 degrees (an angle of 7 degrees,for example).

Other variations are contemplated, which are within the scope of theappended claims. For example, as described above, the plug assembly 150(FIG. 2) includes a tapered surface having a ratcheting profile, and theplug assembly 500 (FIG. 5) includes smooth tapered surfaces. However, inaccordance with further example implementations, a plug assembly mayhave a combination of surfaces. More specifically, referring to FIG. 7,in accordance with some implementations, a plug assembly may have asealing ring 720 and a body member 730, which have tapered surfaces thateach have ratchet teeth and smooth portions. In this regard, as shown inFIG. 7, in accordance with some implementations, the ratchet teeth maybe located on the smaller inner diameter portions, and the smoothportions may be located on the larger inner diameter portions of thesealing ring 720 and body member 730.

Due to this relationship, when the setting tool sleeve 210 forces thesealing ring 720 into the position depicted in FIG. 7, the ratchet teethengage to lock the position of the sealing ring 720 with respect to thebody member 730, and the smooth surfaces engage each other to form afluid seal between the sealing ring 720 and body member 730. Inaccordance with some implementations, the inner surface of the sealingring 720 and the outer surface of the body member 730 may have a taperedangle with respect to the longitudinal axis 201 between 5 to 10 degrees(a tapered angle of 7 degrees, for example).

Referring to FIG. 8, thus, in accordance with example implementations, atechnique 800 to form a fluid barrier inside a tubing string in a wellincludes running (block 804) a plug assembly inside the tubing string;setting (block 808) the plug assembly in response to the application ofan axial force; and using (block 812) a physical engagement of an innerengagement surface of a sealing ring of the plug assembly with an outerengagement surface of a body member of the plug assembly to form a sealbetween the sealing ring and the body member. The technique includesusing (block 816) contact of the outer surface of the ring member withthe tubing string to form a seal between the sealing ring and the tubingstring and secure the sealing ring to the tubing string; and using(block 820) physical interaction between the inner engagement surfaceand the outer engagement surface to retain the ring member in theexpanded state when the axial force is removed.

The plug assembly may be constructed from one or multiple degradable ordissolvable materials, in accordance with example implementations. Inthis manner, although, in accordance with some implementations, the plugassembly may be removed through a milling operation, in accordance withfurther example implementations, one or more components of the plugassembly may include degradable, or dissolvable, materials to create atemporary fluid barrier so that the segment, or zone, inside the tubingstring above the plug assembly may be fractured over a relatively shortwindow of time (a window of one to twelve hours, for example). Afterthese component(s) dissolve, the fluid barrier is thus removed, therebyallowing the through passageway of the plug assembly to allow fluid flowfrom zones below the plug assembly and access through the region of thetubing string in which the fluid barrier was previously formed.

In accordance with some implementations, the untethered object (anactivation ball, for example) may be formed from one or multipledegradable, or dissolvable materials.

Thus, in accordance with example implementations, the plug assemblyand/or untethered object may include one or multiple materials, whichdegrade, or dissolve, after the fracturing operation has been completed.The degradable material(s) of the plug assembly may ideally degrade overa relatively longer time window (a time window of several days, weeks ormonths, as examples) as compared to the time window over which theuntethered object degrades. Thus, a relatively fast dissolvinguntethered object, such as an activation ball, may be deployed to sealthe through passageway of the plug assembly, thereby isolating the zoneabove the plug assembly from other zones below the plug assembly. Aftera well stimulation the relies on the fluid barrier is over, theuntethered object dissolves at a relatively fast rate, and then the plugassembly may dissolve, at a relatively slower rate to completely removethe restriction created by the plug assembly.

In accordance with example implementations, the dissolvable ordegradable material may be the same as one or more of the alloys thatare discussed in the following patents and patent applications, whichhave an assignee in common with the present application: U.S. Pat. No.7,775,279, entitled, “DEBRIS-FREE PERFORATING APPARATUS AND TECHNIQUE,”which issued on Aug. 17, 2010; U.S. Pat. No. 8,211,247, entitled,“DEGRADABLE COMPOSITIONS, APPARATUS COMPOSITIONS COMPRISING SAME, AND AMETHOD OF USE,” which issued on Jul. 3, 2012; PCT Application Pub. No.WO 2016/085798, entitled, “SHAPING DEGRADABLE MATERIAL,” having apublication date of Jun. 2, 2016; PCT Application Pub. No. WO2016/085804, entitled, “SEVERE PLASTIC DEFORMATION OF DEGRADABLEMATERIAL,” having a publication date of Jun. 2, 2016; PCT ApplicationPub. No. WO 2016/085806, entitled, “BLENDING OF WATER REACTIVE POWDERS,”having a publication date of Jun. 2, 2016; PCT Application Pub. No. WO2015/184041, entitled, “DEGRADABLE POWDER BLEND,” having a publicationdate of Dec. 3, 2015; and PCT Application Pub. No. WO 2015/184043,entitled, “DEGRADABLE HEAT TREATABLE COMPONENTS,” having a publicationdate of Dec. 3, 2015.

While the present techniques have been described with respect to anumber of embodiments, it will be appreciated that numerousmodifications and variations may be applicable therefrom. It is intendedthat the appended claims cover all such modifications and variations asfall within the scope of the present techniques.

What is claimed is:
 1. A method comprising: running a plug assemblyinside a tubing string of a well; and setting the plug assembly, whereinsetting the plug assembly comprises: axially, moving a seal member ofthe plug assembly with respect to a body member of the plug assembly tocause an outer engagement surface of the body member to physicallyengage an inner engagement surface of a ring member of the plug assemblyto radially expand the ring member to transition the ring member to anexpanded state and cause an outer surface of the ring member to contactan inner wall of the tubing string; using the physical engagement of theinner engagement surface of the ring member with the outer engagementsurface of the body member to form a seal between the ring member andthe body member; using contact of the outer surface of the ring memberwith the tubing string to form a seal between the ring member and thetubing string and secure the ring member to the tubing string; and usinga physical interaction between the inner engagement surface and theouter engagement surface to retain the ring member in the expanded statewhen the axial force is removed.
 2. The method of claim 1, wherein usingthe physical engagement of the inner engagement surface of the ringmember with the outer engagement surface of the body member to form theseal comprises forming the seal between tapered surfaces.
 3. The methodof claim 1, wherein using the inner engagement surface and the outerengagement surface to retain the ring member in the expanded statecomprises using the physical interaction of tapered surfaces.
 4. Themethod of claim 1, wherein using the physical interaction of the innerengagement surface and the outer engagement surface to retain the ringmember in the expanded state comprises engaging ratchet teeth of thering member and the body member.
 5. A system usable with a wellcomprising: a tubing string; and an untethered object; and a plugassembly, comprising: a body member having a through passageway, thebody member comprising an outer engagement surface and a seat adapted tocatch the untethered object to form a fluid barrier in the tubingstring; and a ring member having a contracted state and an expandedstate, the ring member comprising an inner engagement surface and anouter surface, wherein: the seal member is adapted to axially move withrespect to the body member in response to the application of an axialforce such that the outer engagement surface of the body memberphysically engages the inner engagement surface of the ring member toradially expand the ring member to transition the ring member to theexpanded state and cause the outer surface of the ring member to contactan inner wall of the tubing string; the physical engagement of the innerengagement surface of the ring member with the outer engagement surfaceof the body member forms a seal between the ring member and the bodymember; the contact of the outer surface of the ring member with thetubing string forms a seal between the ring member and the tubing stringand secures the ring member to the tubing string; and the innerengagement surface and the outer engagement surface are adapted tophysically interact to retain the ring member in the expanded state whenthe axial force is removed.
 6. The system of claim 5, wherein the innerengagement surface of the ring member comprises a tapered surface, thering circumscribes a longitudinal axis, and the tapered surface isinclined with respect to the axis by an angle between 5 and 10 degrees.7. The system of claim 5, wherein the inner engagement surface of thering member comprises a ratchet profile.
 8. The system of claim 5,wherein: the inner engagement surface of the ring member comprises afirst tapered surface; the outer engagement surface of the body membercomprises a second tapered surface; and the first and second taperedsurfaces are adapted to form the seal between the ring member and thebody member.
 9. The system of claim 5, wherein: the inner engagementsurface of the ring member comprises a first tapered surface; the outerengagement surface of the body member comprises a second taperedsurface; and the first and second tapered surfaces are adapted toproduce a friction force to retain the ring member in the expanded statewhen the axial force is removed.
 10. The system of claim 5, wherein: theinner engagement surface of the ring member comprises a first taperedsurface and first ratchet teeth; the outer engagement surface of thebody member comprises a second tapered surface and second ratchet teeth;the first and second tapered surfaces are adapted to form the sealbetween the ring member and the body member; and the first and secondratchet teeth are adapted to lock an axial position of the seal memberrelative to the body member to retain the ring member in the expandedstate when the axial force is removed.
 11. An apparatus comprising: abody member having a through passageway, the body member comprising anouter engagement surface; and a ring member having a contracted stateand an expanded state, the ring member comprising an inner engagementsurface and an outer surface, wherein: the seal member is adapted toaxially move with respect to the body member in response to theapplication of an axial force such that the outer engagement surface ofthe body member physically engages the inner engagement surface of thering member to radially expand the ring member to transition the ringmember to the expanded state and cause the outer surface of the ringmember to contact an inner wall of a tubing string; the physicalengagement of the inner engagement surface of the ring member with theouter engagement surface of the body member forms a seal between thering member and the body member; the contact of the outer surface of thering member with the tubing string forms a seal between the ring memberand the tubing string and secures the ring member to the tubing string;and the inner engagement surface and the outer engagement surface areadapted to physically interact to retain the ring member in the expandedstate when the axial force is removed.
 12. The apparatus of claim 11,wherein the body member comprises a slotted metal ring.
 13. Theapparatus of claim 11, wherein the inner engagement surface of the ringmember comprises a tapered surface.
 14. The apparatus of claim 13,wherein the ring member circumscribes a longitudinal axis and thetapered surface is inclined with respect to the axis by an angle between5 and 10 degrees.
 15. The apparatus of claim 11, wherein the innerengagement surface of the ring member comprises a ratchet profile. 16.The apparatus of claim 11, wherein: the inner engagement surface of thering member comprises a first tapered surface; the outer engagementsurface of the body member comprises a second tapered surface; and thefirst and second tapered surfaces are adapted to form the seal betweenthe ring member and the body member.
 17. The apparatus of claim 11,wherein: the inner engagement surface of the ring member comprises afirst tapered surface; the outer engagement surface of the body membercomprises a second tapered surface; and the first and second taperedsurfaces are adapted to produce a friction force to retain the ringmember in the expanded state when the axial force is removed.
 18. Theapparatus of claim 11, wherein: the inner engagement surface of the ringmember comprises a first tapered surface and first ratchet teeth; theouter engagement surface of the body member comprises a second taperedsurface and second ratchet teeth; the first and second tapered surfacesare adapted to form the seal between the ring member and the bodymember; and the first and second ratchet teeth are adapted to lock anaxial position of the seal member relative to the body member to retainthe ring member in the expanded state when the axial force is removed.19. The apparatus of claim 18, wherein: the first ratchet teeth of theinner engagement surface of the ring member is associated with a firstrange of inner diameters of the ring member; the first tapered surfaceof the inner engagement surface of the ring member is associated with asecond range of inner diameters of the ring member; and the diameters ofthe first range of inner diameters are larger than the diameters of thesecond range of inner diameters.
 20. The apparatus of claim 11, whereinthe body member comprises a seat to circumscribe the through passageway,and the seat is adapted to catch an object to form a fluid barrier inthe well.
 21. The apparatus of claim 11, wherein the at least one of theseal members or the body member comprises a degradable materialconstructed to degrade in a time interval less than one month in adownhole environment of the well.